Valvular heart diseases are not usually regarded as a major public-health problem. Our aim was to assess their prevalence and effect on overall survival in the general population. We pooled population-based studies to obtain data for 11 911 randomly selected adults from the general population who had been assessed prospectively with echocardiography. We also analysed data from a community study of 16 501 adults who had been assessed by clinically indicated echocardiography. In the general population group, moderate or severe valve disease was identified in 615 adults. There was no difference in the frequency of such diseases between men and women (p=0.90). Prevalence increased with age, from 0.7% (95% CI 0.5-1.0) in 18-44 year olds to 13.3% (11.7-15.0) in the 75 years and older group (p<0.0001). The national prevalence of valve disease, corrected for age and sex distribution from the US 2000 population, is 2.5% (2.2-2.7). In the community group, valve disease was diagnosed in 1505 (1.8% adjusted) adults and frequency increased considerably with age, from 0.3% (0.2-0.3) of the 18-44 year olds to 11.7% (11.0-12.5) of those aged 75 years and older, but was diagnosed less often in women than in men (odds ratio 0.90, 0.81-1.01; p=0.07). The adjusted mortality risk ratio associated with valve disease was 1.36 (1.15-1.62; p=0.0005) in the population and 1.75 (1.61-1.90; p<0.0001) in the community. Moderate or severe valvular diseases are notably common in this population and increase with age. In the community, women are less often diagnosed than are men, which could indicate an important imbalance in view of the associated lower survival. Valve diseases thus represent an important public-health problem.